Evolution Of Pest Resistance Research Articles

Activation of Bt Protoxin Cry1Ac in Resistant and Susceptible Cotton Bollworm.

Crystalline (Cry) proteins from Bacillus thuringiensis (Bt) are used extensively for insect control in sprays and transgenic plants, but their efficacy is reduced by evolution of resistance in pests. Here we evaluated reduced activation of Cry1Ac protoxin as a potential mechanism of resistance in the invasive pest Helicoverpa armigera. Based on the concentration killing 50% of larvae (LC50) for a laboratory-selected resistant strain (LF120) divided by the LC50 for its susceptible parent strain (LF), the resistance ratio was 1600 for Cry1Ac protoxin and 1200 for trypsin-activated Cry1Ac toxin. The high level of resistance to activated toxin as well as to protoxin indicates reduced activation of protoxin is not a major mechanism of resistance to Cry1Ac in LF120. For both insect strains, treatment with either the trypsin inhibitor N-a-tosyl-L-lysine chloromethyl ketone (TLCK) or the chymotrypsin inhibitor N-a-tosyl-L-phenylalanine chloromethyl ketone (TPCK) did not significantly affect the LC50 of Cry1Ac protoxin. Enzyme activity was higher for LF than LF120 for trypsin-like proteases, but did not differ between strains for chymotrypsin-like proteases. The results here are consistent with previous reports indicating that reduced activation of protoxin is generally not a major mechanism of resistance to Bt proteins.

Pure Bt-crop and mixed seed sowing strategies for optimal economic profit in the face of pest resistance to pesticides and Bt-corn

With the evolution of pest resistance to Bt-corn, farmers’ economic losses are increasing. However, a planting strategy with Bt-corn mixed with non-Bt-corn to fight the development of pest resistance can be efficient. Nevertheless, this mixed strategy poses questions such as (1) what is the optimal ratio of Bt-corn to non-Bt-corn that should be planted in a field? And (2) what is the main factor affecting the farmers’ net present value? To address these questions, we propose and investigate a discrete pest growth model with pest resistance to Bt-corn. According to the model’s economic functions, the main factors affecting the farmers’ net present value are presented and discussed. By comparing the net present values of a pure Bt-corn planting strategy with the mixed planting strategy, an optimal planting strategy was devised. Moreover, the optimal ratio of Bt-corn to non-Bt-corn to be planted when the mixed planting strategy is implemented in the field was also investigated.

Is the possibility of replacing seed dressings containing neonicotinoids with other means of protection viable in major Polish agricultural crops?

Abstract Following the limitations regarding the use of the neonicotinoids: clothianidin, thiamethoxam and imidacloprid there are no currently available insecticide seed dressings for oilseed rape in Poland. For maize here is only one seed dressing containing methiocarb available with a very narrow registered scope of use. The impact of limitations on protection possibilities of other major Polish agricultural crops is either negligible or non-existent. In consequence a group of economically important insect pests of maize [dungbeetles (Melolonthidae); click beetles (Elateridae); noctuid moths (Agrotinae)] and oilseed rape [leaf miners (Agromyzidae), turnip sawfly (Athalia colibri Christ.), cabbage weevils (Curculionidae), cabbage root fly (Hylemyia brassicae Bche.), diamond-back moth (Plutella maculipennis Curt.)] is left without any legal possibility of chemical control. For the other important pests of the early growth stage of oilseed rape development, there are only pyrethroids available together with one product containing chloropiryfos that can be applied once per vegetation season. Since both maize and oilseed rape are grown in Poland on the area of approximately 1 million ha (each crop), this situation raises concerns about production possibilities as well as development of pest resistance.

Pesticide resistance in intensive agricultural fields: a global issue

Pesticide resistance is a genetically based phenomenon and occurs when a pesticide is used on a population containing some individuals that are genetically predisposed to be resistant to that pesticide (BELLINGER 1996). Therefore, resistant individuals probably exist in any natural pest population and the misuse of pesticides tends to select the resistant pests over time. Repeated applications and higher treatment rates will kill increasing numbers of the pest but resistant survivors will pass on the resistance genes to the next generation (BELLINGER 1996). The pesticide selection also occurs at low treatment rates with a relative greater importance on standing genetic variation versus novel mutations on a relatively limited number of individuals and highly resistant individuals are very rare (BISI et al. 2013). In any case, the pest resistance evolution is becoming a global issue on agricultural fields where pesticides have been frequently used in the past 30 years.Resistance may be defined as a heritable change in the sensitivity of a pest population that is reflected in the repeated failure of a product to achieve the expected level of control when used according to the manufacturer’s recommendation for that pest species (IRAC 2015). Natural selection by a pesticide allows some initially very rare, naturally occurring, pre-adapted pests with resistance genes to survive and pass the resistance trait on to their offspring (FRAC 2015, HRAC 2015, IRAC 2015). Through continued application of the pesticide with the same action mechanism, selection for the resistant individuals continues so the proportion of resistant pests in the population increases, while susceptible individuals are eliminated by the pesticide; so that, under permanent selection pressure, resistant pests outnumber susceptible ones and the pesticide is no longer effective (IRAC 2015). In addition, the speed with which resistance develops depends on several factors, including how fast pest reproduction occurs, the capacity of adaptation and survival in the environment, the availability of nearby susceptible populations, the persistence and specificity of the pesticide, and the rate, timing, and number of applications made (FRAC 2015, HRAC 2015, IRAC 2015).The most common pesticide resistances in agricultural fields refer to the resistance of fungi to fungicides, the resistance of insects to insecticides, and the resistance of weeds to herbicides; in spite of the resistance of other pests that can occur, as nematodes, bacteria, mites, and so on). The resistance of fungi, insects, and weeds have been exponentially increasing in the past years around the world (FRAC 2015, HRAC 2015, IRAC 2015), becoming a very important issue in intensive agricultural fields, and mainly in large-scale fields where growers, in almost all cases, depend exclusively on the pesticides to control these organisms.The prevention of the pesticide resistance is currently an obligation for food production worldwide and it has to be based on the reduction of the pressure of selection on a specific pest by the decreasing of both the frequency of using pesticides of the same action mechanism and the frequency of using only pesticides to control the pests. In this way, integrated pest management plays a very important role as a high-effective pest control as well as being the key for the pest resistance prevention. Thus, we obviously must to find management alternatives, in addition to the chemical control, otherwise the agriculture will pass through difficult days in the near future with regards to pest control.

Potential for and consequences of naturalized Bt products: Qualitative dynamics from indirect intransitivities

Advances in genetic modification technology and the production of human-altered genomes have led to an array of genetically modified organisms utilized to address numerous global issues. The human need-based development of these modified organisms often presents unprecedented phenotypes which will interact with the world's existing biodiversity in unknown ways. One such example is Bt transgene crops proliferating because of their application to food security issues due to their resistance to pest insects. While threats to long term viability of Bt crop use due to resistance evolution in pests have been extensively investigated, issues regarding the effects of Bt transgene crops on existing ecosystems and the biodiversity contained therein have seen less scrutiny. In particular, the long-term dynamics in the case of a naturalized Bt product has not received the attention it deserves. Here we note that the ecosystem structure emerging from a naturalized Bt crop is, qualitatively, an intransitive loop. Based on this structure we develop a simple ecosystem model showing that the intransitive nature of the system has potential to facilitate long term persistence of naturalized Bt transgenes by shifting community dynamics.

Zmiany prawne w zakresie ochrony roslin przez amator�w, dostepnosc substancji aktywnych i przewidywany wplyw na rozw�j odpornosci u organizm�w szkodliwych w Polsce

Beginning from June 2015, non-professionals will be allowed to only buy and use plant protection products bearing information on the label that they are intended for use by non-professionals. Based on the current register and derogations, the following products will be available for use by amateurs: 21 fungicides, 30 insecticides and 15 herbicides with respectively 20, 14 and 9 different active substances. Over a third of the mentioned active substances of fungicides and insecticides are classified as “high risk” in terms of probability of pest resistance development. For numerous uses only a single product is available. The area of home gardens in Poland amounts to 53.5 thousand hectares. Sales of plant protection products for use by amateurs is about 7% of the market value. The very limited availability of chemical plant protection products for non-professionals can be a serious problem if seen from the perspective of pest resistance development and dissemination. Resistant pests may also affect farms with commercial production. Poland is an important producer of a variety of fruits, vegetables and ornamental plants with a very limited availability of chemical protection. Resistance development can further reduce the practical means of pest control and became a serious economic problem.

Development of transgenic Brassica napus with an optimized cry1C* gene for resistance to diamondback moth (Plutella xylostella)

Wang, Y., Zhang, Y., Wang, F., Liu, C. and Liu, K. 2014. Development of transgenic Brassica napus with an optimized cry1C* gene for resistance to diamondback moth (Plutella xylostella). Can. J. Plant Sci. 94: 1501–1506. Bacillus thuringiensis (Bt) cry1Ac gene has been transformed into rapeseed to control diamondback moth (DBM, Plutella xylostella), which is one of the major lepidopteran pests of rapeseed (Brassica napus). However, Cry1A-resistant DBM populations have already developed in the field. Cry1C* is a new synthetic Bt gene based on the original cry1Ca5 sequence through optimizing its codons as well as removing AT-rich sequences and inverted repeats. In our present study, the cry1C* gene was introduced into rapeseed via Agrobacterium-mediated transformation, and a total of 42 transgenic lines were recovered. The results of polymerase chain reaction (PCR) and Southern blot both confirmed the expression of the cry1C* gene in the genomes of the transformants. We also assessed the expression of this foreign gene at the mRNA level in some selected transgenic lines by real-time reverse transcription (RT) PCR analysis. Enzyme-linked immunosorbent assay (ELISA) showed that the Cry1C* expression at the protein level greatly varied among individual transgenic plants, and transgenic line 1C-8 had the highest protein level of 799.32 ng g−1. The transgenic rapeseed plants expressing cry1C* gene showed a high efficacy against DBM. Taken together, the cry1C*-transgenic rapeseed could be employed as a useful germplasm in pest management and in the broad bioinsecticidal spectrum to prevent and postpone the development of pest resistance.

Present and future potential of plant-derived products to control arthropods of veterinary and medical significance

The use of synthetic pesticides and repellents to target pests of veterinary and medical significance is becoming increasingly problematic. One alternative approach employs the bioactive attributes of plant-derived products (PDPs). These are particularly attractive on the grounds of low mammalian toxicity, short environmental persistence and complex chemistries that should limit development of pest resistance against them.Several pesticides and repellents based on PDPs are already available, and in some cases widely utilised, in modern pest management. Many more have a long history of traditional use in poorer areas of the globe where access to synthetic pesticides is often limited. Preliminary studies support that PDPs could be more widely used to target numerous medical and veterinary pests, with modes of action often specific to invertebrates.Though their current and future potential appears significant, development and deployment of PDPs to target veterinary and medical pests is not without issue. Variable efficacy is widely recognised as a restraint to PDPs for pest control. Identifying and developing natural bioactive PDP components in place of chemically less-stable raw or 'whole’ products seems to be the most popular solution to this problem. A limited residual activity, often due to photosensitivity or high volatility, is a further drawback in some cases (though potentially advantageous in others). Nevertheless, encapsulation technologies and other slow-release mechanisms offer strong potential to improve residual activity where needed.The current review provides a summary of existing use and future potential of PDPs against ectoparasites of veterinary and medical significance. Four main types of PDP are considered (pyrethrum, neem, essential oils and plant extracts) for their pesticidal, growth regulating and repellent or deterrent properties. An overview of existing use and research for each is provided, with direction to more extensive reviews given in many sections. Sections to highlight potential issues, modes of action and emerging and future potential are also included.

Dual invasion analysis: a general model of novel ecological dynamics due to Bt product and resistant pests in wild settings

Transgenic Bt crops have been integrated as a central component of the agricultural policies of many nations across the globe due to their insecticidal properties. While focus on increased yield resulting from the use of Bt crops has overshadowed the concerns of pest populations developing resistance, resistance has been recently discovered in even highly managed fields. One issue that has received less attention is the resulting set of ecological dynamics from escaped Bt products into wild settings. I present a differential equation model of the ecological interaction between a wild plant–pest community and an invading Bt toxin-producing plant and the ensuing evolution of pest resistance. Key to this model investigation is the assumption of energy costs with both the production of Bt toxin by Bt plants and the resistance to Bt toxin exhibited by resistant pest individuals. Results show that persistence of the initial invading Bt plant population is possible through an intransitive loop dynamic. Furthermore, coexistence of wild-type plants and pests as well as Bt-producing plants and resistant pests is possible through the dynamics resultant from energy trade-offs.

Efficacy of Genetically Modified Bt Toxins Alone and in Combinations Against Pink Bollworm Resistant to Cry1Ac and Cry2Ab

Evolution of resistance in pests threatens the long-term efficacy of insecticidal proteins from Bacillus thuringiensis (Bt) used in sprays and transgenic crops. Previous work showed that genetically modified Bt toxins Cry1AbMod and Cry1AcMod effectively countered resistance to native Bt toxins Cry1Ab and Cry1Ac in some pests, including pink bollworm (Pectinophora gossypiella). Here we report that Cry1AbMod and Cry1AcMod were also effective against a laboratory-selected strain of pink bollworm resistant to Cry2Ab as well as to Cry1Ab and Cry1Ac. Resistance ratios based on the concentration of toxin killing 50% of larvae for the resistant strain relative to a susceptible strain were 210 for Cry2Ab, 270 for Cry1Ab, and 310 for Cry1Ac, but only 1.6 for Cry1AbMod and 2.1 for Cry1AcMod. To evaluate the interactions among toxins, we tested combinations of Cry1AbMod, Cry1Ac, and Cry2Ab. For both the resistant and susceptible strains, the net results across all concentrations tested showed slight but significant synergism between Cry1AbMod and Cry2Ab, whereas the other combinations of toxins did not show consistent synergism or antagonism. The results suggest that the modified toxins might be useful for controlling populations of pink bollworm resistant to Cry1Ac, Cry2Ab, or both.

Comparing Terpenes from Plant Essential Oils as Pesticides for the Poultry Red Mite (Dermanyssus gallinae)

Resistance to conventional synthetic pesticides has been widely reported in ticks, parasitic mites and other pests of veterinary and medical significance. New and novel approaches to manage these pests are therefore needed to ensure efficient control programmes that can be implemented now and in the future. Recent research in this area has focused on the pesticidal potential of plant essential oils. These products are attractive as pesticide candidates on the grounds of low mammalian toxicity, short environmental persistence and complex chemistries (limiting the development of pest resistance against them). Although issues may exist concerning reliability in efficacy of essential oils, these may be overcome by identifying and developing bioactive oil components for use in pest management. In the current work, three such components (terpenes) found in essential oils (eugenol, geraniol and citral) were tested against the poultry red mite Dermanyssus gallinae. All provided 100% mortality in toxicity tests when undiluted. Even at 1% of this dose, eugenol was 20% effective against experimental pest populations, although the remaining terpenes were largely ineffective at this concentration.

Insect resistance to Bt crops: lessons from the first billion acres

Evolution of resistance in pests can reduce the effectiveness of insecticidal proteins from Bacillus thuringiensis (Bt) produced by transgenic crops. We analyzed results of 77 studies from five continents reporting field monitoring data for resistance to Bt crops, empirical evaluation of factors affecting resistance or both. Although most pest populations remained susceptible, reduced efficacy of Bt crops caused by field-evolved resistance has been reported now for some populations of 5 of 13 major pest species examined, compared with resistant populations of only one pest species in 2005. Field outcomes support theoretical predictions that factors delaying resistance include recessive inheritance of resistance, low initial frequency of resistance alleles, abundant refuges of non-Bt host plants and two-toxin Bt crops deployed separately from one-toxin Bt crops. The results imply that proactive evaluation of the inheritance and initial frequency of resistance are useful for predicting the risk of resistance and improving strategies to sustain the effectiveness of Bt crops.

Maize Farmers Perceptions towards Organic Soil Management Practices in Bungoma County, Kenya

The objective of the study was to evaluate maize farmers' perceptions towards organic soil management practices in Bungoma County. A simple random sampling technique was used to select a sample of 650 smallholder farmers and primary data was collected using observations and interviews with the help of a semi-structured schedule. In the analysis, a Likert-type five-point continuum scale was used to rank farmers perceptions with one (1) as the most and five (5) as the worst check. The results showed that farmers were invariably concerned about the environment and were interested in protecting agricultural resources both for the present use and for future generations. Application of green manure and cultivation of legume crops were perceived to improve soil fertility and soil structure. Further, agrochemicals were perceived to have a negative effect on both human and animal health and their over-application leads to development of pest resistance to pesticides. The study revealed a relationship between perception towards organic soil management practices and some socio-economic and institutional factors such as age, education, household size, extension, training and farm distance. The study recommends policy interventions in enhancing farmers' awareness through training and technical advice on organic farming practices through agricultural extension services and developing information networks among farmers.

Assessment of Calotropis Procera Aiton and Datura alba Nees Leaves Extracts as Bio-Insecticides Against Tribolium castaneum Herbst in Stored Wheat Triticum Aestivum L.

Plant materials have been used for pest control for centuries but recently, preservation of cereals products in storage has relied upon chemical insecticides to control stored grain pests but having drawbacks of toxicity to non-target organisms, human health hazards, development of pest resistance and environmental pollution. The present study was conducted to control the serious cereal’s (wheat) stored grains pest Tribolium castaneum Herbst. Calotropi sprocera Aiton (Ak) and Datura alba (Dhatura) have been reported by many researchers as natural insecticides against stored grain pests. Five concentrations of leaf extracts of C. sprocera and D. alba (20%, 40%, 60%, 80% and 100%) were compared to see their efficiency to control Tribolium castaneum. Different parameters like repellency, growth inhibition, mortality rate, infestation/spoilage of grains, insect population and losses in grain weight were tested after application of treatments. Three months storage of wheat grains showed maximum repellency, mortality at higher concentrations of C. sprocera and D. alba, but there was less infestation/ spoilage, loss in grain weight and insect population at higher concentrations (80%,100%).

Bioactivity of Essential Oil from Zingiber officinale (Zingiberaceae) Against Three Stored-Product Insect Species

The indiscriminate use of synthetic pesticides has given rise to many serious problems, including toxicity to nontarget organisms, development of pest resistance and resurgence and environmental contamination. So during past three decades, the scientists have looked for less persistent and biodegradable alternatives. Essential oils from aromatic plants are recognized as proper alternatives. In this experiment, toxicity of Zingiber officinale (Roscoe) essential oil that was isolated via hydrodistillation was investigated against adults of the red flour beetle, Tribolium castaneum (Herbst) and larvae of the Mediterranean flour moth, Ephestia kuehniella (Zell.) and Indianmeal moth, Plodia interpunctella (Hübner). Repellency of this oil on all the three pest species adults was also studied. In determination of fumigant toxicity, the LC50 value for T. castaneum was calculated 374.95 μL/L air after 48 hr of exposure. As well, LC50 for E. kuehniella and P. interpunctella after 9 hr were calculated 258.95 and 69.05 μL/L air, respectively. In contact toxicity assay, LC50 value for E. kuehniella and P. interpunctella were determined as 0.61 and 0.81 μL/cm2, respectively. Relationship between exposure time and oil concentration on mortality of all species indicated that mortality was increased by increasing of the oil concentration and exposure time. Repellency of this oil on all the insect species was significant.

The potential of beneficial microorganisms in agricultural systems

The potential of beneficial microorganisms in agricultural systems

Seeds of Change: Corn Seed Mixtures for Resistance Management and Integrated Pest Management

The use of mixtures of transgenic insecticidal seed and nontransgenic seed to provide an in-field refuge for susceptible insects in insect-resistance-management (IRM) plans has been considered for at least two decades. However, the U.S. Environmental Protection Agency has only recently authorized the practice. This commentary explores issues that regulators, industry, and other stakeholders should consider as the use of biotechnology increases and seed mixtures are implemented as a major tactic for IRM. We discuss how block refuges and seed mixtures in transgenic insecticidal corn, Zea mays L., production will influence integrated pest management (IPM) and the evolution of pest resistance. We conclude that seed mixtures will make pest monitoring more difficult and that seed mixtures may make IRM riskier because of larval behavior and greater adoption of insecticidal corn. Conversely, block refuges present a different suite of risks because of adult pest behavior and the lower compliance with IRM rules expected from farmers. It is likely that secondary pests not targeted by the insecticidal corn as well as natural enemies will respond differently to block refuges and seed mixtures.

Entomotoxic effect of silica nanoparticles against Sitophilus oryzae (L.)

Fumigants and residual insecticides are commonly used to combat stored grain pests. In recent years, consumer awareness of the health hazard from residual toxicity and the growing problem of insect resistance to these conventional insecticides have led the researchers to look for alternative strategies for stored grains protection. For example, diatomaceous earth (DE) can be effective against stored grain insects. In this study, DE was used to design amorphous nano sized hydrophilic, hydrophobic, and lipophilic silica in 15–30 nm size range. Nanocides are expected to reduce the volume of application and kinetics of development of resistance in pests. We hypothesized that surface-functionalized silica nanoparticle (SNP) might be a viable alternative to conventional pesticides. Entomotoxicity of SNP was tested against rice weevil Sitophilus oryzae and its efficacy was compared with bulk-sized silica (individual particles larger than 1 μm). Amorphous SNP was found to be highly effective against this insect pest causing more than 90% mortality, indicating the effectiveness of SNP to control insect pests.

실행방식 측면에서 살충제의 신중한 사용에 의한 저항성 발달의 관리

해충의 저항성발달로 야기되는 문제를 해결하기 위한 정보를 제공함으로써 향후연구를 촉진시키고자 하였다. 농약사용이 지속되는 한 저항성 발달은 필연적이라는 생각으로, 저항성발달을 지연시키기 위해 재배자가 활용할 수 있는 약제성질에 근거를 둔 약종선택, 혼용, 교호, 모자이크 처리 등 약제살포법과, 천적과 양립할 수 있는 선택성 살충제와 저항성 천적의 이용을 중심으로 한 병해충 종합관리(IPM)에 대해 고찰하였다. 저항성관리에 약종의 성질을 이용할 경우 약종별로 작용점과 mode of action(작용방식)이 같거나 다를 수 있고, 2차 해충과 함께 살충제의 활성, 잔류기간, 약제 저항성 발달에 대한 취약성도 다르다. 약제는 섭식, locomotion(거동), 비행, 교미, 포식자 회피 등에도 영향을 미치므로 종합적으로 고려하여 역교차저항성을 나타내는 살충제의 사용이 바람직하다. 농약혼용은 실제 많이 이루어지고 있고 앞으로도 그러하겠지만, 진정한 의미에서 저항성 발달 지연을 위한 혼용, 교호, 모자이크 처리법은 대립유전자의 우성도, 교차저항성, 유입(immigration), fitness 불이익 등과 함께 살충제의 작용방식과 작용점들의 차이에서 구성약제가 매우 높은 비율로 충을 죽이는 부의 교차저항성을 가진 살충제들의 채택에 대하여 논의하였다. 저항성 관리에 약제혼용의 대표적인 사례 22가지와 교호처리 사례 27가지를 표로 제시하였다. 혼용처리의 잠재적 불이익은 생물적 방제의 와해, 이차해충의 저항성발달, 고도의 저항성 개체군 선발, 다양한 살충제에 대한 교차저항성 범위 확대를 내포하고 있다. 교호처리는 살포약량을 높이거나 낮추고, 다른 대사기구를 가진 살충제를 사용하는 것도 고려되었다. 모자이크 처리는 진딧물 같이 정주성 해충인 경우에 연관없는 살충제를 교호로 다른 구역에 처리하거나, 살충제 처리한 열(列)과 그렇지 않은 것을 혼합 배치하여 저항성 발달을 지연시키거나 피해를 감소시킬 수 있다. 해충의 저항성 진화 측면에서 볼 때, 기생자와 포식자의 저항성과 선택성은 농약처리를 요하는 세대 수를 감소시키고 농약으로부터 피난처의 상보적 역할을 수행할 수 있다. 작물별, 기주별, 기생자와 포식자에게 선택성을 보이는 약제를 별도의 표로 요약하여 제시하였다. 기생자의 생존력 향상을 위해 살충제의 선택성과 선택성에 영향을 주는 내 외적 요인에 대하여 검토하였다. 농약사용 하에서 기생자를 사용하기 위해 농약에 대해 저항성이거나 내성이 있는 기생자를 검정, 채집 혹은 선발하는 것을 논의하였다. 포식자에 대한 선택독성에 영향을 미치는 요인들로 농약의 선택성, 선택성의 포장적용과 그에 미치는 요인, 포식자와 기주의 균형, 선택성을 도외시한 방제법의 문제점, 천적과 농약의 양립성 등에 대하여 논의하였다. An attempt was made to stimulate future research by providing exemplary information, which would integrate published knowledge to solve specific pest problem caused by resistance. This review was directed to find a way for delaying resistance development with consideration of chemical(s) nature, of mixture, rotation, or mosaics, and of insecticide(s) compatible with the biological agents in integrated pest management (IPM). The application frequency, related to the resistance development, was influenced by insecticide activity from potentiation, residual period, and the vulnerability to resistance development of chemical, with secondary pest. Chemical affected feeding, locomotion, flight, mating, and predator avoidance. Insecticides with negative cross-resistance by the difference of target sites and mode of action would be adapted to mixture, rotation and mosaic. Mixtures for delaying resistance depend on each component killing very high percentage of the insects, considering allele dominance, cross-resistance, and immigration and fitness disadvantage. Potential disadvantages associated with mixtures include disruption of biological control, resistance in secondary pests, selecting very resistant population, and extending cross-resistance range. The rotation would use insecticides in high and low doses, or with different metabolic mechanisms. Mosaic apply insecticides to the different sectors of a grid for highly mobile insects, spray unrelated insecticides to sedentary aphids in different areas, or mix plots of insecticide-treated and untreated rows. On the evolution of pest resistance, selectivity and resistance of parasitoids and predator decreased the number of generations in which pesticide treatment is required and they could be complementary to refuges from pesticides To enhance the viability of parasitoids, the terms on the insecticides selectivity and factors affecting to the selectivity in field were examined. For establishment of resistant parasitoid, migration, survivorship, refuge, alternative pesticides were considered. To use parasitoids under the pressure of pesticides, resistant or tolerant parasitoids were tested, collected, and/or selected. A parasitoid parasitized more successfully in the susceptible host than the resistant. Factors affecting to selective toxicity of predator are mixing mineral oil, application method, insecticide contaminated prey, trait of individual insecticide, sub-lethal doses, and the developmental stage of predators. To improve the predator/prey ratio in field, application time, method, and formulation of pesticide, reducing dose rate, using mulches and weeds, multicropping and managing of surroundings are suggested. Plant resistance, predator activity, selective insect growth regulator, and alternative prey positively contributed to the increase of the ratio. Using selective insecticides or insecticide resistant predator controlled its phytophagous prey mites, kept them below an economic level, increased yield, and reduced the spray number and fruits damaged.

THE IR-4 PROGRAM: HELPING THE U.S. BLUEBERRY INDUSTRY CONTROL HIGH-PRIORITY INSECT, DISEASE, AND WEED PESTS

THE IR-4 PROGRAM: HELPING THE U.S. BLUEBERRY INDUSTRY CONTROL HIGH-PRIORITY INSECT, DISEASE, AND WEED PESTS